Separate gathering Delta changes and validation.

pkg/analyzer/test/src/context/context_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.test.src.context.context_test;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 3452 matching lines @@
     _assertValidForChangedLibrary(a);
     _assertInvalid(a, LIBRARY_ERRORS_READY);
     _assertValidForDependentLibrary(b);
     _assertValidAllResolution(b);
     _assertInvalidHintsVerifyErrors(b);
 
     _performPendingAnalysisTasks();
     expect(context.getErrors(b).errors, hasLength(1));
   }
 
+  void test_sequence_dependenciesWithCycles() {
+    Source a = addSource(
+        '/a.dart',
+        r'''
+const A = 1;
+''');
+    Source b = addSource(
+        '/b.dart',
+        r'''
+import 'c.dart';
+const B = C1 + 1;
+''');
+    Source c = addSource(
+        '/c.dart',
+        r'''
+import 'a.dart';
+import 'b.dart';
+const C1 = A + 1;
+const C2 = B + 2;
+''');
+    Source d = addSource(
+        '/d.dart',
+        r'''
+import 'c.dart';
+const D = C2 + 1;
+''');
+    _performPendingAnalysisTasks();
+    // Update "A" constant.
+    // This should invalidate results in all sources.
+    context.setContents(
+        a,
+        r'''
+const A = 2;
+''');
+    _assertInvalid(a, LIBRARY_ERRORS_READY);
+    _assertInvalid(b, LIBRARY_ERRORS_READY);
+    _assertInvalid(c, LIBRARY_ERRORS_READY);
+    _assertInvalid(d, LIBRARY_ERRORS_READY);
+  }
+
   void test_sequence_inBodyChange_addRef_deltaChange() {
     Source a = addSource(
         '/a.dart',
         r'''
 class A {
 }
 ''');
     Source b = addSource(
         '/b.dart',
         r'''
@@ skipping 823 matching lines @@
    * Initialize the visitor.
    */
   _ElementGatherer();
 
   @override
   void visitElement(Element element) {
     elements[element] = element;
     super.visitElement(element);
   }
 }